Egypt has informed the United Nations of its airstrikes into Libyan territory describing the action as self-defence after the killing of Christians last Friday.

Egypt’s foreign ministry said in a statement handed to the U.N. Security Council on Saturday that its airstrikes targeting terrorist hideouts in Libya are in accordance with the law.

“The airstrikes that targeted the locations of terrorist organisations in Derna, eastern Libya, are in line with Article 51 of the UN Charter on self-defence and with the Security Council’s resolutions concerning terrorism,” the statement cited by local media Ahram said.

The first airstrike was conducted on Friday near Derna in eastern Libya hours after the 29 Coptic Christians were killed in their bus by masked men who opened fire at close range.

The airstrikes that targeted the locations of terrorist organisations in Derna, eastern Libya, are in line with Article 51 of the UN Charter on self-defence and with the Security Council’s resolutions concerning terrorism.

The air force planes further launched strikes on Saturday targeting militant training camps which the Egyptian authorities claim were used by the gunmen.

Witnesses told Reuters on Monday that warplanes carried out another three air strikes. No military immediately confirmed Monday’s strikes.

Islamic State claimed responsibility for Friday’s attack in Egypt, the latest targeting Christian minority there following two church bombings last month that killed more than 45, also claimed by the group.